A Mayo Clinic study finds that two-thirds of people treated for cat bites to the hand need to be hospitalized because of infection.

Cat bites might not look serious, but they can lead to severe infections and even hospitalization, according to a recent Mayo Clinic study.

Although cats have no more bacteria in their mouths than dogs, cats' teeth typically penetrate the skin deeper, pushing germs into tissue and joints and making them more likely to cause infection.

"It can be just a pinpoint bite mark that can cause a real problem because the bacteria get into the tendon sheath or into the joint where they can grow with relative protection from the blood and immune system,” study senior author Dr. Brian Carlsen said in a news release.

Bites on the hand are particularly dangerous. Researchers looked at nearly 200 patients treated for a cat bite to the hand from 2009 to 2011 and found that two-thirds of them were hospitalized.

"When the cat bites the hand, the joints and tendons are protected with fluid and there is no circulation so bacteria can grow like crazy, making treatment longer in some case," Carlsen told USA Today.

Antibiotic treatment failed in 21 of the 193 patients, who later required surgery to flush out the infection. Middle-aged women were the most common bite victims.

Carlsen advises people to pay close attention to cat-bite wounds, especially those to the hand or wrist, and monitor them for redness or swelling.

"It may look like a pin prick, but the rule of thumb is go see a doctor if a cat bites your hand," he said.